1. Field of the Invention
The present invention is directed to a linear data input transducer for use in a holographic data storage system and the system. The system comprises a laser generating a laser beam, a beam divider which splits the beam from the laser into an object beam and a reference beam, the transducer which is arranged in the path of the object beam to spatially modulate the object beam with the information to be modulated thereon and a holographic plate on which both the reference beam and the modulated object beam are projected to record the holographic information.
2. Prior Art
Linear acousto-optical data input transducers for high speed data input into a holographic storage system are known and discussed in an article printed in Proceedings of the Electro-Optical Systems Design Conference, New York, September 18-20, 1973, pages 90-101. As disclosed in this article, a piezo-electric transducer of an acousto-optical modulator receives the information, which is to be stored, in the form of pulse modulated high-frequency signals in a serial fashion. The piezo-electric transducer creates a correspondingly modulated high frequency ultrasonic wave which passes through the modulator at the speed of sound. As soon as the entire modulated sound wave fills the aperture of the modulator, the modulator is illuminated with an extremely short laser pulse and during the duration of the laser pulse, the sound wave is virtually not moving. The pattern of the sound wave causes a diffraction of the laser beam. The spatially modulated, first optical order of diffraction of the laser beam is focused by a lens onto the part of the storage tape or medium on which the recording is to be made. A disadvantage with the above described data transducer and recording system is that it requires a laser having a pulse in the order of a nano-second pulse.